The invention refers to mounting/bearing device for a fifth wheel as disclosed in the generic portion of Claim 1.
The mounting/bearing for a fifth wheel represents the connection between the coupling plate and the substructures, such as bearing pedestals, mounting plates, lift or displacement devices. These are components which support the fifth wheel and are themselves connected to the vehicle frame. The connection must transfer all forces that occur during operation. Furthermore, it must be possible for the fifth wheel to swivel around the lateral axis of the vehicle by at least 12xc2x0 as compensation when traveling over uneven ground. With respect to hitching operations with light and empty trailers, it is important that the swivel motion be very easy to initiate. If the mounting/bearing is too stiff, the weight of the trailer may not be sufficient to move an inclined coupling into a position parallel to the bottom of the trailer during hitching. As a result, the king pin is not properly positioned relative to the locking mechanism in the fifth wheel, interfering with the closure of the fifth wheel. A smooth-running mounting/bearing is generally achieved by means of a bolted connection.
Such a mounting/bearing for a fifth wheel is disclosed in the German patent application with the file number 199 52 997.2-21, which discloses a fastening device having a bearing pedestal and a bearing element that interacts with the bearing pedestal, which bearing element can be fastened to a coupling plate of the fifth wheel. The rubber pillow arranged between the bearing pedestal and the bearing element, however, is fabricated from a solid material and thus swiveling of the coupling plate is only possible with the exertion of great force.
DE 44 02 526 A1 discloses a mounting/bearing device for a fifth wheel wherein the connection between the coupling plate and the bearing pedestal is realized by means of a bolt, over which an elastic sleeve or xe2x80x9crubber bushingxe2x80x9d is pulled. This type of connection requires complex machining of the coupling plate, bolt and bearing pedestal. The coupling plate swivels stiffly due to the solid material and large friction surfaces.
DE 30 40 925 C2 describes a fifth wheel wherein the articulating function is realized by means of rubber elements. The elasticity of the rubber is utilized to ensure a certain mobility between the bearing pedestal and coupling plate. The coupling plate can be swiveled by displacing the rubber. This type of mounting/bearing for a displacement coupling is very cost-effective to produce, but swivels stiffly due to the large amount of force required to displace the rubber.
DE 23 03 163 B discloses the generic prior art. The mounting/bearing for a fifth wheel described therein comprises a fifth wheel plate supported by a bearing pedestal, which mounting/bearing is fastened to the bottom of the fifth wheel plate by means of a bar extending through the bearing pedestal. The bar has on the bearing pedestal end a fixing device for the fastening of a solid rubber strip intended to dampen any occurring impacts and loads. Like the displacement coupling described above, the solid rubber strip permits swiveling of the fifth wheel only with the exertion of great force.
Another damping element described in DE 23 03 163 B comprises a rubber tube that, when assembled, is completely filled by a bolt and thus cannot or can only slightly facilitate a walking movement.
It is therefore the object of the current invention to create a smooth running mounting/bearing device for a fifth wheel that does not require costly and complex reworking of the components.
To achieve this object, the current invention teaches that the walking element contains at least one cavity when assembled. A walking element is preferably understood as an elastic element that can still roll in the deformed, in particular the compressed, state.
Installation of a walking element thus ensures the smooth swiveling of the fifth wheel. Examples of preferred materials are rubber, polyurethane or spring steel. The advantage of these is that the installation space can be produced with large manufacturing tolerances. Mechanical reworking of the contact surfaces in the area of the bridge and the stirrup-shaped bearing pedestal are not necessary, as the elasticity of the walking element provides tolerance compensation.
A preferred embodiment of the walking element is characterized by the fact that the walking element is tubular and contains at least one cavity parallel to the lateral axis of the fifth wheel. The tubular shape of the contact surfaces of the walking element enables improved rolling, i.e. walking, of the walking element.
This movement can be performed with the exertion of relatively little force.
A further advantage of the tubular shape of the walking element is that changes in the diameter of the walking element are more easily tolerated than is the case with a solid material because of the manufacturing tolerances. A favorable configuration includes at least one cavity of the walking element that is so large that the inner surfaces of the walking element do not rub against one another, even in the as-installed condition. Rubbing together of the inner surfaces of the walking element hampers the walking movement and under certain circumstances would increase walking element wear.
It is advantageous if the walking element and the stirrup-shaped bearing pedestal or the bridge to include molded elements for the positive/form-fit fixing of the walking element. In a preferred embodiment, the outer surface of the walking element contains at least one nub that engages in a recess in the stirrup-shaped bearing pedestal or the bridge. The nub can be molded onto that side of the walking element facing the stirrup-shaped bearing pedestal and engage in the stirrup-shaped bearing pedestal. Another plausible embodiment has a recess in the walking element and a nub on the stirrup-shaped bearing pedestal or bridge. The positive/form-fit connection of the walking element to the stirrup-shaped bearing pedestal or the bridge is an installation aid during assembly of the fifth wheel and ensures proper positioning of the walking element between the stirrup-shaped bearing pedestal and the bridge.
A preferred embodiment of the mounting/bearing device for a fifth wheel is characterized by the fact that the walking element is fastened to the bridge or the stirrup-shaped bearing pedestal. The connection can be realized as a temporary adhesive connection for the period of installation. The adhesive connection offers the advantage of easy installation, as the rubber pillow can be installed together with the bridge and without shifting or falling off.
An advantageous embodiment has a U-shaped bridge. The U-shape of the bridge and the stirrup-shaped bearing pedestal together define the installation space for the walking element and also pretension the walking element.
In a favorable embodiment, the curvature of the bridge cross-section in the contact area of the walking element with the bridge and the stirrup-shaped bearing pedestal is matched to the stirrup-shaped bearing pedestal such that a wedge-shaped installation space is formed. As the swivel angle around the lateral axis of the vehicle increases, the edge of the walking element is more highly compressed by the wedge-shaped installation space, limiting the walking movement. With proper material selection and design of the walking element, the wedge-shaped installation space establishes a return moment in the direction of the start position, so that the fifth wheel returns to a position parallel to the underside of the trailer. This is advantageous when hitching a light or empty trailer.
It is advantageous if the bridge comprises two arms and a connecting web, whereby the connecting web has a step-like projection in at least one area between the walking element the arm. In the event of tensile loading of the fifth wheel, such as occurs in curves, the step-like projection acts as an end stop and protects the walking element against damage.
A preferred embodiment is characterized by at least two retaining elements protruding circumferentially on the inner surface of the stirrup-shaped bearing pedestal. These retaining elements help to limit the movement of the walking element around the lateral axis of the vehicle and fix the position of the walking element in the bearing pedestal.